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Re: [Amps] Alpha &&DX Conversion

To: amps@contesting.com
Subject: Re: [Amps] Alpha &&DX Conversion
From: "Joe Subich, W4TV" <lists@subich.com>
Date: Wed, 05 Sep 2012 23:39:04 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>

Yup, I had another one ... a McMartin with an 8877.  2300W output on
104.9 just outside Columbus, OH while I was in school and my first
job out of college.

73,

   ... Joe, W4TV


On 9/5/2012 10:37 PM, Jim W7RY wrote:
Yup! Mee too.

I worked on a BEXT 2500 watt transmitter with an 8877. My transmitter
was limited to 2200 watts output because of licensing. 24 hours a day!
As I remember about 65 or 70 watts from the exciter. Plate voltage was
4100 V under load.

73
Jim W7RY


-----Original Message----- From: Paul Christensen
Sent: Wednesday, September 05, 2012 2:48 PM
To: amps@contesting.com
Subject: Re: [Amps] Alpha &&DX Conversion

"I will tell you why i run a 2 tuber, you put in 25 watts in and do
1500 easy not push a one tuber to do 1500 out. it all comes down to
what you can afford. bill 73"

This may be an interesting point of reference.  During my college years,
I worked at a 3KW FM station in Rockford, IL as its chief engineer.  The
transmitter was an AEL FM-2.5K (FCC type accepted to 2.5KW output) and
used a single 8877 to produce 2500-watts output at 104.9 MHz.  All day
long, every day, 365 days a year.   A three-bay circularly polarized
antenna brought ERP to 3KW.

If a 77Dx is running intermittent amateur-class service but under high
duty-cycle modes like RTTY at 1500-watts output (the U.S. legal limit,
for example), I think its reasonable to assume that a 8877 is already
operating with sufficient headroom of roughly 1KW.   For what purpose do
any of us need more than 1KW of headroom from our vacuum tubes when
producing 1.5KW?

Paul, W9AC
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